Industrial shredding equipment is known and used, for example, in the recycling industry to break apart large objects into smaller parts that can be more readily processed. In addition to shredding material like rubber (e.g., car tires), wood, and paper, commercial shredding systems are available that can shred large ferrous materials, such as scrap metal, automobiles, automobile body parts, and the like.
FIG. 1A illustrates an example shredding system as is known and in use in the art, and FIG. 1B illustrates a more detailed view of a conventional shredding head or rotors that may be used in such a shredding system. More specifically, as shown in FIG. 1A, this example shredding system 100 includes a material inlet system (such as chute 102) that introduces the material 104 to be shredded to the shredding chamber 106. The material 104 to be shredded may be of any desired size or shape, and, if desired, it may be heated, cooled, crushed, baled, or otherwise pretreated prior to introduction into the shredding chamber 106. If necessary or desired, the inlet system 102 may include feed rollers or other machinery to help push or control the rate at which the material 104 enters into the chamber 106, to help hold the material 104 against an anvil 108, and/or to help keep the material 104 from moving backward up the chute 102. A disc rotor is shown, however, other rotors, such as spider and barrel, are also commonly used, and this invention may be equally useful with those types of rotors.
A rotary shredding head 110 (rotatable about axis or shaft 110A) is mounted in the shredding chamber 106. As the head 110 rotates, the shredding hammers 112 extend outward and away from the rotational axis 110A of the head 110 due to centrifugal force (as shown in FIG. 1A, and as will be explained in more detail below). As they rotate, the shredder hammers 112 impact the material 104 to be shredded between the hammer 112 and the anvil 108 (or other hardened surface provided within the shredding system 100) in order to break apart the material 104. The construction of one conventional shredding head 110 will be described in more detail below in conjunction with FIG. 1B. As the material 104 is shredded, it may be discharged from the shredding chamber 106 through one of the outlets 114, e.g., provided in the bottom, top, or side of the chamber 106 walls, and transported in some manner (generally shown by arrows 116, such as via gravity, via conveyors, via truck or other vehicle, etc.) for further processing (e.g., further recycling, reclamation, separation, or other processing).
FIG. 1B provides a more detailed view of an example shredding head 110 that may be used in the shredding system 100 of FIG. 1A. This example shredding head 110 is made from multiple rotor disks 120 that are separated from one another by spacers 122 mounted around the drive shaft 110A. While any number of rotor disks 120 may be provided in a shredding head 110 (e.g., 2-25), this illustrated example includes seven disks 120 (the end disk 120 is omitted to better show the details of the underlying structures). The disks 120 may be fixedly mounted with respect to the shaft 110A (e.g., by welding, mechanical connectors, etc.) to allow the disks 120 to be rotated when the shaft 110A is rotated (e.g., by an external motor or other power source, not shown). In addition to providing a spacing function, spacers 122 can help protect the shaft 110A from undesired damage, e.g., due to contact with material 104 being shredded, broken parts of a shredder hammer 112, etc.
Hammer pins 124 extend between at least some of the rotor disks 120 (more commonly, between several disks 120 and/or through the entire length of the head 110), and the shredder hammers 112 are rotatably mounted on and are rotatable with respect to these pins 124. More specifically, as shown in FIG. 1B, a hammer pin 124 extends through an opening 112A provided in the mounting portion 112F of the shredder hammer 112, and the shredder hammer 112 is capable of rotating around this pin 124. In this illustrated example, the shredding head 110 includes six hammer pins 124 around the circumference of the rotor disks 120, and a single shredder hammer 112 is provided on each pin 124 between two adjacent rotor disks 120 (such that each hammer pin 124 includes a single shredder hammer 112 mounted thereon and such that the shredder hammers 112 are staggeringly distributed along the longitudinal length of the head 110). This hammer pattern may be modified as required by the end user, depending on their needs. At locations between rotor disks 120 where no shredder hammer 112 is provided on a particular hammer pin 124, the pin 124 may be covered with a pin protector 126, to protect the pin structure 124 from contact with and damage caused by the material 104 being shredded. These pin protectors 126, which may be of any desired size and/or shape, also may function (if desired) as a spacer between adjacent rotor disks 120.
In use, the rotor disks 120 are rotated as a unit about shaft 110A, e.g., by an external motor or other power source (not shown). The centrifugal force associated with this rotation causes the shredder hammers 112 to rotate about their respective pins 124 to extend their heavier blade ends 112E outward and away from the shaft 110A, as shown in FIG. 1A. As the rotation continues, the shredder hammer 112 will contact the material 104 to be shredded. Because it is rotatably mounted on the hammer pin 124, contact with the material 104 to be shredded may cause the shredder hammer 112 to slow down or even rotate in the opposite direction as it smashes the material 104 to be shredded against the anvil 108. The pins 124, pin protectors 126, hammers 112, spacers 122, and rotor disks 120 may be structured and arranged so that, in the event that a shredder hammer 112 is unable to completely pass through the material 104, it can rotate to a location between adjacent plates 120 and thereby pass by the material 104 until it is able to extend outward again under the centrifugal force due to rotation of the shredder head 110 about shaft 110A for the next collision. Also, in some instances, the shredder hammer 112 will shift sideways on its pin 124 as it passes by or through the material to be shredded. If desired, the various parts of the shredder head 110 may be shaped and oriented with respect to one another such that a shredder hammer 112 can rotate 360° around its pin 124 without contacting another pin 124, a pin protector 126, the drive shaft 110A, another hammer 112, etc. Shredding systems and heads of the types described above are known and used in the art.
As is evident from the above description, shredder hammers 112 are exposed to extremely harsh conditions of use. Thus, shredder hammers 112 typically are constructed from hardened steel materials, such as low alloy steel or high manganese alloy content steel (such as Hadfield Manganese Steel, containing about 11 to 14% manganese, by weight). Such materials are known and used in the art, such as in shredder hammers commercially available from ESCO Corporation of Portland, Oreg. Even when such hardened materials are used, the typical lifespan of a shredder hammer 112 may be a few days to a few weeks (e.g., depending, of course, on various factors, such as the material being shredded, amount of use, etc.). The shredder hammer blade or impact area 112E will tend to wear away over time and over repeated collisions with the material 104 to be processed, as shown in broken lines in FIG. 3, while the shredder hammer's mounting area 112F (the end where the hammer pin 124 is mounted) typically is hidden between adjacent rotor disks 120 and is not exposed to the material 104 being shredded (except perhaps at the exposed exterior edges and outer circumference of the disks 120).
FIGS. 2A and 2B show enlarged views of the edges of the openings 112A provided in shredder hammers 112 to receive the hammer pins 124. As shown in these figures, while the majority of the side walls 112B of these openings 112A are straight, flat, and parallel to one another in the axial direction L, the very corners 112C of the side wall 112B forming the opening 112A (i.e., where the interior side walls 112B meet the major surfaces 112D of the hammer 112) may be beveled (FIG. 2A) or rounded (FIG. 2B). These features may make it somewhat easier to insert the hammer pins 124 into the openings 112A, particularly when the diameter of the pin 124 is close in size to the diameter of the openings 112A (e.g., the curved or sloped corners 112C somewhat “funnel” the pin 124 into the opening 112A).
As noted above, shredder hammers 112 are exposed to extremely harsh conditions in use. The shredder hammers 112 themselves may weigh several hundred pounds (e.g., 150 to 1500 lbs). Moreover, these heavy hammers 112 slam into the material 104 to be shredded at relatively high rates of speed, and the material 104 to be shredded may constitute very hard materials, such as automobiles, automobile parts, etc. This slamming action and sideways movement of the shredder hammer as it impacts the material to be shredded causes repeated and highly stressful contact between the pin 124 and the side walls 112B of the pin openings 112A in the shredder hammers 112, particularly at the corners 112C of these openings 112A. While shredder hammers 112 typically are constructed from hardened steel materials, as noted above, shredder hammers 112 still often tend to develop cracks C in the mounting area 112F, as shown in FIG. 3, which can lead to early failure of the hammer 112 (e.g., before the blade area 112E is fully utilized). This early failure substantially increases costs in both parts and labor, and substantially slows and delays shredding operations.
Accordingly, there is room in the art for improvements in the structure and construction of shredder hammers and the machinery and systems utilizing such hammers.